One Of The Largest Icebergs On Record In The Making

A very large crack is forming in the Larsen C Ice Shelf on the Antarctic Peninsula. The crack is up to 1,500 feet wide and will most likely generate one of the largest icebergs on record. Only 6.4 miles of ice are keeping the ice sheet from calving off an iceberg that is basically the size of Delaware. Researchers who have been studying the ice melt (Project MIDAS) estimate that although the exact timing of the calving event in unclear, it could occur easily within the next few months. In fact, scientists noted that the crack spread another approximately six miles during the second half of December 2016. From January 1st to January 19th, the crack expanded again, and now only 6.4 miles of unbroken ice remains. Once the calving event occurs, scientists are concerned that it will destabilize the Larsen C ice sheet to the point of its disintegration.

The current location of the rift on Larsen C, as of January 19, 2017. Labels highlight significant jumps. Tip positions are derived from Landsat (USGS) and Sentinel-1 InSAR (ESA) data. Background image blends BEDMAP2 Elevation (BAS) with MODIS MOA2009 Image mosaic (NSIDC). Other data from SCAR ADD and OSM (update on graphic from Freedman, based on Project MIDAS data).

British Antarctic Survey (BAS) recently captured the following video footage of the immense crack in the Larsen C Ice Shelf:

Ice Melt, Sea Level Rise, and Superstorms

Dr. James Hansen (Director of Climate Science, Awareness and Solutions Program Earth Institute, Columbia University) and 18 co-authors just published an article – Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 °C global warming could be dangerous – in the journal Atmospheric Chemistry & Physics. Their article is significant because not only does it raise the issues of superstorms and sea level rise that are associated with human forcing of climate change, but their research also suggests that current climate models do not adequately gauge the effects of ice melt runoff from the Antarctic and Greenland ice sheets. The video embeded below is done by Dr. Hansen and his co-authors and is a good abstract of their recent research findings.

IPCC Hones Its Language on Climate Change

The Athabasca Glacier, a part of the Columbia Icefields in Alberta, Canada, is receding on an average of 16 feet per year.
The Athabasca Glacier, a part of the Columbia Icefields in the Rocky Mountains of Alberta, Canada, has receded 0.93 miles (1.5 km) over the last 125 years.

Yesterday the Intergovernmental Panel on Climate Change (IPCC) released its latest Synthesis Report (SYR5) – a summary of the IPCC’s Fifth Assessment Report (AR5) on the state of knowledge on climate change. The big news with the SYR5’s release is the change in language used within the report – words like “unequivocable” and “clear” now replace the earlier usage of “probable” and “likely” when describing global warming and the role that human activity has played in the temperature increase. Text from the SYR5 underscores this major language shift:

 “Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, and sea level has risen.”

…and

“Human influence on the climate system is clear, and recent anthropogenic emissions of greenhouse gases are the highest in history.”

The SYR5 summarizes IPCC’s three other major reports on various facets of climate change that were released in 2013-2014. These reports are all available from the IPCC website:

  • Climate Change 2013 – The Physical Science Basis;
  • Climate Change 2014 – Impacts, Adaptations, and Vulnerability; and
  • Climate Change 2014 – Mitigation of Climate Change.

The Carbon Brief 11/2/2014 blog gives a listing and good, brief descriptions of what else is noteworthy in the SYR5. Here’s a quick recap on their list:

  • Global warming continues unabated
  • Human influence on warming is clear
  • Ocean acidification, sea level rise, glacial ice decline
  • IPCC’s new carbon budget
  • Consequences of inaction – climate change impacts
  • Low carbon transition – costs and savngs

Greenland’s Fastest Glacier Now Flowing At Record Speeds

Jakobshavn Isbræ, Greenland’s fastest flowing glacier, has been moving even faster over the past several years. The Jakobshavn Glacier, or Jakobshavn Isbræ, is located on the west coast of Greenland and drains a major part of the Greenland ice sheet into a deep ocean fjord. Accordingly, the Jakobshavn Glacier could add significantly to sea level rise.

Recorded speeds of glacial flow during the summer of 2012 topped out at more than 17 kilometers per year, or over 46 meters per day. In fact, the transient summer speeds observed for 2012 probably represent the fastest observed speeds for any outlet glacier or ice stream in Greenland or Antarctica. In a paper published recently in The Cryosphere, Joughin and others, note that:

We have extended the record of flow speed on Jakobshavn Isbræ through the summer of 2013. These new data reveal large seasonal speedups, 30 to 50% greater than previous summers. At a point a few kilometres inland from the terminus, the mean annual speed for 2012 is nearly three times as great as that in the mid-1990s, while the peak summer speeds are more than a factor of four greater. These speeds were achieved as the glacier terminus appears to have retreated to the bottom of an over-deepened basin with a depth of 1300m below sea level. The terminus is likely to reach the deepest section of the trough within a few decades, after which it could rapidly retreat to the shallower regions 50 km farther upstream, potentially by the end of this century.

The warming trend in the Arctic correlates with Greenland’s glaciers thinning and retreating progressively inland. The rapid retreat of the Jakobshavn Isbræ, however, is due not only to the warming trend, but to a number of feedbacks. The primary control on the glacial flow now is the physical location of the glacier’s calving front. The calving front is currently located in a deep area of its outlet fiord, an area where the underlying rock bed is about 1300 meters below sea level. As the glacier loses ice in this area – basically the ice in front that is holding back the flow – the flow speeds up.

The contribution to sea level rise from the Jakobshavn Isbræ may be significant. One of the study’s authors, Ian Joughlin, is quoted in Science Daily, 2/3/2014, as saying:

We know that from 2000 to 2010 this glacier alone increased sea level by about 1 mm. With the additional speed it likely will contribute a bit more than this over the next decade.

So what should we expect for the Jakobshavn Isbræ’s future? Joughlin and others summarized this by:

Thus, the potential for large losses from Greenland is likely to be determined by the depth and inland extent of the troughs through which its outlet glaciers drain. These features are only beginning to be well resolved by international efforts such as NASA’s Operation IceBridge. The relatively sparse data collected thus far indicate that, with its great depths and inland extent, Jakobshavn’s Isbræ is somewhat unique (Bamber et al., 2013), suggesting that it may be difficult for the majority of Greenland’s outlet glaciers to produce or to sustain such large increases in ice discharge.

Of interest may be an earlier Geopostings on “Chasing Ice” that showed a 2012 huge calving event from the Jakobshavn Isbræ.